Inferring origin of mercury inclusions in quartz by multifractal analysis
Summary: In order to refine our understanding of how fluid inclusions were trapped in the host minerals, we observed mercury inclusions in quartz samples using X-ray computed tomography technique. We obtained three-dimensional spatial distributions, and analyzed them using fractal and multifractal methods. Given the fractal dimension and its implied mechanism, the mercury-bearing fluids were not primary fluid inclusions, but migrated into the pre-existing cracks of quartz crystals by diffusion processes.
On the data-driven inference of modulatory networks in climate science: an application to West African rainfall
Summary: We applied coupled heterogeneous association rule mining (CHARM), Lasso
multivariate regression, and dynamic Bayesian networks to find relationships
within a complex system, and explored means with which to obtain a consensus
result from the application of such varied methodologies. Using this fusion of approaches, we identified relationships among climate factors that fall into two categories: well-known associations from prior knowledge, and putative links that invite further research.
D. L. González II, M. P. Angus, I. K. Tetteh, G. A. Bello, K. Padmanabhan, S. V. Pendse, S. Srinivas, J. Yu, F. Semazzi, V. Kumar, and N. F. Samatova Nonlin. Processes Geophys., 22, 33-46, 2015 AbstractFull Article (PDF, 3622 KB)Discussion Paper (NPGD)Special Issue
Dependence of sandpile avalanche frequency–size distribution on coverage extent and compactness of embedded toppling threshold heterogeneity: implications for the variation of Gutenberg–Richter b value
L.-Y. Chiao and Q. Liu Nonlin. Processes Geophys., 21, 1185-1193, 2014 AbstractFull Article (PDF, 166 KB)
05 Dec 2014
Large eddy simulation of sediment transport over rippled beds
An improved ARIMA model for precipitation simulations
Summary: This paper presents an improvement on the conventional ARIMA model for precipitation time-series forecast. The precipitation time series of 12 months is first classified into several clusters. The maxima, minima, and truncation means of each cluster are then predicted using the improved ARIMA models, which are further used to predict the monthly precipitation through a set of regression models. A case study demonstrates that the present approach could increase the forecast accuracy by 21%.
Instability and change detection in exponential families and generalized linear models, with a study of Atlantic tropical storms
Summary: It is rarely ensured that the parameters of statistical distributions are stable through the entire duration of a data collection process. A failure of stability leads to nonsmoothness and nonlinearity in the physical processes. We propose testing for stability of parameters of exponential family distributions and generalized linear models. We study Atlantic tropical storms using the techniques developed here.
Correlations between climate network and relief data
Summary: In the past few years, complex networks have been extensively applied to climate sciences, yielding
the new field of climate networks. Here, we generalize climate network analysis by investigating the influence of altitudes in network topology. More precisely, we verified that nodes group into different communities corresponding to geographical areas with similar relief properties. This new approach may contribute to obtaining more complete climate network models.
Long-term changes in the north–south asymmetry of solar activity: a nonlinear dynamics characterization using visibility graphs
Summary: We use visibility graphs to characterize asymmetries in the dynamics of sunspot areas in both solar hemispheres. Our analysis provides deep insights into the potential and limitations of this method, revealing a complex interplay between effects due to statistical versus dynamical properties of the observed data. Temporal changes in the hemispheric predominance of the graph connectivity are found to lag those directly associated with the total hemispheric sunspot areas themselves.
Estimation of sedimentary proxy records together with associated uncertainty
Summary: We present a new approach to estimating sedimentary proxy records along with the proxy uncertainty. We provide analytical expressions for the proxy record, while transparently propagating uncertainties from the ages to the proxy record. We represent proxies on an error-free, precise timescale. Our approach provides insight into the interrelations between proxy variability and the various uncertainties. We demonstrate our method with synthetic examples and proxy data from the Lonar lake in India.
B. Goswami, J. Heitzig, K. Rehfeld, N. Marwan, A. Anoop, S. Prasad, and J. Kurths Nonlin. Processes Geophys., 21, 1093-1111, 2014 AbstractFull Article (PDF, 4239 KB)
11 Nov 2014
Finding recurrence networks' threshold adaptively for a specific time series